I have the HiBebe one and got it from ebay...was going to rent, but since we want more than one (and I am completely paranoid

), we decided to buy it instead...and it had pretty good reviews...
I think it said that you could start hearing the H/B between 10-12 weeks, but I have a very retroverted uterus, so everything is way far back...I heard baby on it for the first time at 12 1/2 weeks (it would have been earlier if baby wasn't so far back)...
For the next few weeks, it would take me a long time to find him, but starting at about week 15 or so, I could hear him every time without having to search long at all...
I still do it every night (just for like 20 seconds, so I dont bug him too much)...I LOVE the security it gives me